Study of gambogenic acid-induced apoptosis of melanoma B16 cells through PI3K/Akt/mTOR signaling pathways

Abstract

To discuss the mechanism of gambogenic acid (GNA) in inducing the apoptosis of melanoma B16 cells. The inhibitory effect of GNA on the proliferation of B16 cells was measured by the methyl thiazolyl tetrazolium (MTT) assay. The effect of GNA on B16 cells was detected by the Hoechst 33258 staining. The transmission electron microscopy was used to observe the ultra-structure changes of B16 cells. The changes in PI3K, p-PI3K, Akt, p-Akt, p-mTOR, PTEN proteins were detected by the Western blotting to discuss the molecular mechanism of GNA in inducing the apoptosis of B16 cells. GNA showed a significant inhibitory effect in the growth and proliferation of melanoma B16 cells. The cell viability remarkably decreased with the increase of GNA concentration and the extension of the action time. The results of the Hoechst 33258 staining showed that cells processed with GNA demonstrated apparent apoptotic characteristics. Under the transmission electron microscope, B16 cells, after being treated with GNA, showed obvious morphological changes of apoptosis. The Western blot showed a time-dependent reduction in the p-PI3K and p-Akt protein expressions, with no change in p-PI3K and p-Akt protein expression quantities. The p-mTOR protein expression decreased with the extension of time, where as the PTEN protein expression showed a time-dependent increase. GNA could inhibit the proliferation of melanoma B16 cells and induce their apoptosis within certain time and concentration ranges. Its mechanism in inducing the cell apoptosis may be related to PI3K/Akt/mTOR signaling pathways.